1. Field of the Invention
The present invention relates to a data driving circuit, an Organic Light Emitting Diode (OLED) display using the data driving circuit, and a method of driving the OLED display, and more particularly, to a data driving circuit to display an image with a desired brightness, an OLED display using the data driving circuit, and a method of driving the OLED display.
2. Description of the Related Art
Various flat panel displays have recently been developed as alternatives to a relatively heavy and bulky Cathode Ray Tube (CRT) display. The flat panel display includes a Liquid Crystal Display (LCD), a Field Emission Display (FED), a Plasma Display Panel (PDP), an Organic Light Emitting Diode Display (OLED), etc.
Among the flat panel displays, the OLED display can emit light for itself by electron-hole recombination. Such an OLED display has advantages in that its response time is relatively fast and its power consumption is relatively low. Generally, the OLED display employs a transistor provided in each pixel for supplying a current corresponding to a data signal to a light emitting device, thereby allowing the light emitting device to emit light.
An OLED display comprises: a pixel portion including a plurality of pixels formed in a region defined by the intersection of scan lines and data lines; a scan driver to drive the scan lines; a data driver to drive the data lines; and a timing controller to control the scan driver and the data driver.
The timing controller generates a Data Control Signal (DCS) and a Scan Control Signal (SCS) corresponding to an external synchronization signal. The DCS and the SCS are supplied from the timing controller to the data driver and the scan driver, respectively. Furthermore, the timing controller supplies external data to the data driver.
The scan driver receives the SCS from the timing controller. The scan driver generates scan signals on the basis of the SCS and supplies the scan signals to the scan lines.
The data driver receives the DCS from the timing controller. The data driver generates data signals on the basis of the DCS and supplies the data signals to the data lines while synchronizing with the scan signals.
The display portion receives first and second voltages from an external power source, and supplies them to the respective pixels. When the first voltage and the second voltage are supplied to the pixels, each pixel controls a current corresponding to the data signal to flow from a first voltage line to a second voltage line via the light emitting device, thereby emitting light corresponding to the data signal.
That is, in this OLED display, each pixel emits light with a predetermined brightness corresponding to the data signal, but cannot emit light with the desired brightness because transistors provided in the respective pixels have different threshold voltages. Furthermore, in this OLED display, there is no method of measuring and controlling a real current flowing in each pixel in correspondence to the data signal.